George Bush last night laid out his case for another term in the White House, claiming only he would keep America safe from a "drift towards tragedy" in a world scarred by terrorism.

Half of his hour-long speech at Madison Square Garden in acceptance of his party's nomination to run again for office was devoted to defending his domestic record and promising a modernised tax and welfare system.

But the biggest cheers from delegates, as well as tears, came as he outlined his vision for America abroad.

"I believe the most solemn duty of the American president is to protect the American people. If America shows uncertainty and weakness in this decade the world will drift towards tragedy. This will not happen on my watch," he said.

"I am running for president with a clear and positive plan to build a safer world and a more hopeful America."

In keeping with the themes of the week, he played heavily on his personal involvement with the victims of the September 11 attacks and described their profound impact on his strength and resolve.

"Since that day I wake up every morning thinking about how to better protect our country. I will never relent in defending America, whatever it takes."

While he outlined specific initiatives for domestic policy, such as a simplified federal tax code and the construction of 7m more homes over the next 10 years, his foreign policy agenda was heavy on rhetoric and decidedly light on detail.

In Iraq and Afghanistan "our strategy is succeeding", he said, adding that America needed to play a central role in overseeing the democratisation of the entire region.

"Free societies in the Middle East will be hopeful societies, which no longer feed resentments and breed violence for export ... I am proud that our country remains the hope of the oppressed and the greatest force for good on this Earth."

Despite repeatedly praising the efforts and sacrifice of America's armed forces, he gave no indication as to how or when they might begin the journey home.

His attacks on his Democratic opponent were measured, compared with the full-frontal assault by his vice-president, Dick Cheney, the night before.

He drove home the Republicans' portrayal of John Kerry as a pandering, indecisive liberal who insulted America's allies in the war on terror by referring to them in the context of Iraq as a "coalition of the coerced and the bribed".

At a midnight rally in his home state of Massachusetts, Senator Kerry responded to the president's speech in unprecedented style, comparing his own Vietnam war record with his rival's less dangerous posting with the Texas Air National Guard.

"They have attacked my patriotism and my fitness to serve as commander in chief," he told the cheering crowd. "I'm not going to have my commitment to defend this country questioned by those who refused to serve when they could have and by those who have misled the nation into Iraq."

President Bush did, however, have something good to say about one centre-left politician: mention of Tony Blair's support brought a warm round of applause from the crowd.

Delegates were distracted twice again last night by outbursts from individual protesters during the speech. Dozens of extra secret service and security staff were on hand to eject the two female agitators while delegates drowned out their cries with chants of "Four more years".

Osama bin Laden, who remains at large, did not merit a mention, but George Bush had no such qualms about again seeking to justify his decision to invade Iraq and topple Saddam Hussein.

"Do I forget the lessons of September 11 and take the word of a madman or do I take action to defend our country?" he asked. "Faced with that choice, I will defend America every time."

With the Israeli-Palestinian "road map" for peace long abandoned by his administration, Mr Bush expressed an optimistic belief that the democratic potential of a new Afghanistan and Iraq would soon rub off: "Palestinians will hear the message that democracy and reform are within their reach and so is peace with our good friend Israel," he said.

The president, who has spent months attending to the party's rightwing base, last night portrayed himself as the custodian of a "compassionate conservative philosophy" as well as the defender of religious-based ideology.

To huge cheers from the large numbers of delegates who campaign against abortion and regard their stance as an essential part of the Republican platform, he said that in a "caring society ... we must make a place for the unborn child."

On the contentious but equally emotive issue of gay marriage he had another chunk of red meat to throw from his purpose-built, circular stage in the centre of the auditorium. "I support the protection of marriage against activist judges," he said, tapping into the rage that many in the hall feel towards the Massachusetts supreme court, which legalised same-sex marriage earlier this year.

As his speech neared its close, the president made a rare foray into self-examination: "Even when we don't agree, at least you know what I believe and where I stand," he said. "You may have noticed I have a few flaws, too: people sometimes have to correct my English. I knew I had a problem when Arnold Schwarzenegger started doing it."

"Now and then I come across as a little too blunt, and for that we can all thank the white-haired lady sitting right up there," he added, pointing towards his mother, Barbara.

As he outlined his record in office there was no talk of the 1.1m job losses that Democrats still hope might undermine the obvious authority being a war president bestows. Mr Bush instead painted a selective picture of a rosy economy that has turned the corner.

To distract from the continuing grim statistics on jobs he threw in initiatives to provide new health centres for every "poor" county in the land, though there was no indication of how this would be paid for in a time of federal spending cuts.

He also outlined populist measures to curtail huge cash settlements against doctors in malpractice suits, which drive up insurance premiums.

But to bring the Republicans' seamlessly produced convention narrative to a close, he returned once again to his main argument: America will only heal with four more years of nurturing from Mr Bush.

"To everything we know, there is a season - a time for sadness, a time for struggle, a time for rebuilding. And now we have reached a time for hope. This young century will be liberty's century."

The president was clearly nervous beneath the surface, even fluffing his final line before the deafening roar of approval released the first of the traditional end-of-convention balloons.

His manner was strangely introspective, hinting perhaps at a new confidence that the election is now his to lose.

Delegates filed out into the Manhattan night relieved that their sojourn in the Democratic citadel was over.

Looking at the exhausted faces of policemen, security officers and even the odd protester left behind on the subway system, you could tell the feeling was mutual.

Whether the Bush mission to demolish the credibility of his Democrat rival has been accomplished will only become clear in the tough weeks of swing state campaigning that lie ahead.